by Ann Oldenburg, USA TODAY

by Ann Oldenburg, USA TODAY

While she wore a slinky red dress, her fiance was more music casual, wearing a baseball hat and T-shirt.

When asked about the CBS guidelines that had been sent out warning Grammy stars that "buttocks and female breasts" need to be covered, and obscenity on clothing will not be permitted, Kat Von D, told E!'s Giuliana Rancic, "We don't care about guidelines."

But apparently someone made Deadmau5 adhere to them, because the S on his hat had been blacked out. While on camera talking to Rancic, it said, "Your hit bums me out."

He also wore the hat (with the S intact) when Kat snapped a photo of him in the new Porsche 911 Carrera S she gave him for his birthday last month.